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Issue #9530: Fix undefined-behaviour-inducing overflow checks in bytes and bytearray implementations.

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This commit is contained in:
Mark Dickinson 2010-08-10 18:35:01 +00:00
parent 331ea92ade
commit cf940c701f
3 changed files with 49 additions and 68 deletions
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57
Objects/bytesobject.c
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@ -579,13 +579,14 @@ PyBytes_Repr(PyObject *obj, int smartquotes)
static const char *hexdigits = "0123456789abcdef";
register PyBytesObject* op = (PyBytesObject*) obj;
Py_ssize_t length = Py_SIZE(op);
size_t newsize = 3 + 4 * length;
size_t newsize;
PyObject *v;
if (newsize > PY_SSIZE_T_MAX || (newsize-3) / 4 != length) {
if (length > (PY_SSIZE_T_MAX - 3) / 4) {
PyErr_SetString(PyExc_OverflowError,
"bytes object is too large to make repr");
return NULL;
}
newsize = 3 + 4 * length;
v = PyUnicode_FromUnicode(NULL, newsize);
if (v == NULL) {
return NULL;
@ -732,12 +733,12 @@ bytes_repeat(register PyBytesObject *a, register Py_ssize_t n)
/* watch out for overflows: the size can overflow int,
* and the # of bytes needed can overflow size_t
*/
size = Py_SIZE(a) * n;
if (n && size / n != Py_SIZE(a)) {
if (n > 0 && Py_SIZE(a) > PY_SSIZE_T_MAX / n) {
PyErr_SetString(PyExc_OverflowError,
"repeated bytes are too long");
return NULL;
}
size = Py_SIZE(a) * n;
if (size == Py_SIZE(a) && PyBytes_CheckExact(a)) {
Py_INCREF(a);
return (PyObject *)a;
@ -1687,30 +1688,28 @@ replace_interleave(PyBytesObject *self,
{
char *self_s, *result_s;
Py_ssize_t self_len, result_len;
Py_ssize_t count, i, product;
Py_ssize_t count, i;
PyBytesObject *result;
self_len = PyBytes_GET_SIZE(self);
/* 1 at the end plus 1 after every character */
count = self_len+1;
if (maxcount < count)
/* 1 at the end plus 1 after every character;
count = min(maxcount, self_len + 1) */
if (maxcount <= self_len)
count = maxcount;
else
/* Can't overflow: self_len + 1 <= maxcount <= PY_SSIZE_T_MAX. */
count = self_len + 1;
/* Check for overflow */
/* result_len = count * to_len + self_len; */
product = count * to_len;
if (product / to_len != count) {
PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long");
return NULL;
}
result_len = product + self_len;
if (result_len < 0) {
assert(count > 0);
if (to_len > (PY_SSIZE_T_MAX - self_len) / count) {
PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long");
return NULL;
}
result_len = count * to_len + self_len;
if (! (result = (PyBytesObject *)
PyBytes_FromStringAndSize(NULL, result_len)) )
@ -1939,7 +1938,7 @@ replace_single_character(PyBytesObject *self,
char *self_s, *result_s;
char *start, *next, *end;
Py_ssize_t self_len, result_len;
Py_ssize_t count, product;
Py_ssize_t count;
PyBytesObject *result;
self_s = PyBytes_AS_STRING(self);
@ -1953,18 +1952,13 @@ replace_single_character(PyBytesObject *self,
/* use the difference between current and new, hence the "-1" */
/* result_len = self_len + count * (to_len-1) */
product = count * (to_len-1);
if (product / (to_len-1) != count) {
assert(count > 0);
if (to_len - 1 > (PY_SSIZE_T_MAX - self_len) / count) {
PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long");
return NULL;
}
result_len = self_len + product;
if (result_len < 0) {
PyErr_SetString(PyExc_OverflowError,
"replacment bytes are too long");
return NULL;
}
result_len = self_len + count * (to_len - 1);
if ( (result = (PyBytesObject *)
PyBytes_FromStringAndSize(NULL, result_len)) == NULL)
@ -2007,7 +2001,7 @@ replace_substring(PyBytesObject *self,
char *self_s, *result_s;
char *start, *next, *end;
Py_ssize_t self_len, result_len;
Py_ssize_t count, offset, product;
Py_ssize_t count, offset;
PyBytesObject *result;
self_s = PyBytes_AS_STRING(self);
@ -2024,18 +2018,13 @@ replace_substring(PyBytesObject *self,
/* Check for overflow */
/* result_len = self_len + count * (to_len-from_len) */
product = count * (to_len-from_len);
if (product / (to_len-from_len) != count) {
PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long");
return NULL;
}
result_len = self_len + product;
if (result_len < 0) {
assert(count > 0);
if (to_len - from_len > (PY_SSIZE_T_MAX - self_len) / count) {
PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long");
return NULL;
}
result_len = self_len + count * (to_len-from_len);
if ( (result = (PyBytesObject *)
PyBytes_FromStringAndSize(NULL, result_len)) == NULL)